1. Field of the Invention
This invention is related to a overfill protection device and in particular to one which can prevent the gas pressure in a tank from going beyond the limits.
2. Description of the Prior Art
It has been found that the conventional overfill protection device utilizes a helical spring to push a piston upwardly to close a gas inlet so that the gas inlet will be opened only when the pressure applied to the piston by the gas being filled into a tank exceeds the pressure applied to the piston by the spring, and the gas inlet will be automatically shut off when the pressure within the tank exceeds a predetermined level. Furthermore, the piston is provided with a narrow passage for gas purging. Nevertheless, such a overfill protection device suffers from the following drawbacks:
1. Low gas supply capacity; PA1 2. Long purging time; and PA1 3. High in cost.
Therefore, it is an object of the present invention to provide an improved overfill protection device which can obviate and mitigate the above-mentioned drawbacks.